.px2rem(@name, @px){
    @{name}: @px / 75 * 1rem;
}
*{padding: 0;margin: 0;}
html, body{
    height: 100%;
}
body{
    display: flex;
    flex-direction: column;
}
.section{
    flex: 1;
    overflow: auto;
    position: relative;
    .sec{
        height: 100%;
        img{
            width: 100%;
            height: 100%;
        }
    }
}
span{
    position: absolute;
    top: 40%;
    left: 30%;
} 